The present invention relates to a measurement apparatus, a measurement method, and a correction method, and particularly to a measurement apparatus and a measurement method for measuring the amount of eccentricity at the time when a wafer is rotated on a table and to a correction method.
In an apparatus in which a disc-shaped object, for example, a wafer is sucked on a table and rotated around the axis of rotation of the table, it is necessary to accurately measure the amount of eccentricity of the wafer for scanning the wafer around the axis of rotation.
For example, Japanese Unexamined Patent Application Publication Nos. 2006-201360, 2013-171042, 2009-121911, 2009-085766, 2000-294608, 2007-206441, and 2016-045117 each disclose an apparatus that images the end portion of a wafer rotated on a table.
The methods disclosed in Japanese Unexamined Patent Application Publication Nos. 2006-201360, 2013-171042, 2009-121911, 2009-085766, and 2000-294608 each include determining the shape of the wafer by observing the end portion of the wafer and therefore requires time for the determination of the shape of the wafer or requires a large number of components, such as a plurality of light sources.
The methods disclosed in Japanese Unexamined Patent Application Publication Nos. 2007-206441 and 2016-045117 each include translating the wafer in accordance with an error in circularity of the wafer or an error in position where the wafer is placed, for focusing error control. Since the amount of eccentricity is not correlated with the position along the end portion, the accuracy in the measurement of the amount of eccentricity cannot therefore be improved.
The methods disclosed in the related art therefore have difficulty in measuring the amount of eccentricity of a disc-shaped object supported by a rotating table with accuracy at low cost.
The present invention has been made to solve the problems described above, and an object of the present invention is to provide a measurement apparatus and a measurement method for measuring the amount of eccentricity of a disc-shaped object supported by a rotating table with accuracy at low cost and further provide a correction method.